I've had this same question. Well I either fall right into White's desired play or, as you mentioned, it's symmetical and boring.
I asked John Bartholomew in the comments section of one of his YouTube vids about a good plan for Black in these structures (against White's Stonewall Attack). He mentioned that one good plan for Black is to try to organize the e5 pawn break. I actually had some nice success with that in the very next game I played (although the comp showed me afterwards that I was too hasty trying to do it).
I have an annoyingly hard time playing against Stonewall-type pawn setups, as either black or white.
I'm actually ok as the aggressor who uses the Stonewall to build an attack - Valeri Lilov did a set of good youtube videos on it explaining how to build a kside attack after setting up the Stonewall pawns (Rook lift, queen shift, etc.)
I however would like some strategic ideas to disrupt the 'typical' Stonewall kside aggression, and hopefully unbalance the position.
I don't think I'm losing disproportionately against the Stonewall, it's just my games almost end up symmetric and boring and obvious by the middlegame. Both of us try and plant that advanced Stonewall central N, and then we both trade it off at some point. CPU says we're usually near equal, and it's often not obvious how to proceed from these equal positions.